Method of aiding the reservation of resources for a packet network, and associated management device and aid device

ABSTRACT

A method intended to aid in the reservation of resources within a packet-switched communication network comprising a number N of relaying nodes. This method consists i), in determining for some at least of the N nodes at least one resource reservation plan Pik defined by a plan identifier associated with a stream identifier and at least two ports, and ii) in memorizing for each of the N nodes the various plans Pik relating to them.

TECHNICAL DOMAIN OF THE INVENTION

The invention relates to “packet-switched network” type communicationnetworks, and more specifically to aid in the reservation of resourceswithin such networks.

“Resource” is understood here to mean any type of variable thatcharacterizes a data flow exchanged between two nodes of a communicationcore network via a given infrastructure. It can therefore notably (andnot restrictively) be the minimum and/or maximum bandwidth, the jitter,the latency, the minimum and/or maximum size of transmitted packets orthe number of consecutive packets per burst.

Moreover, “stream” is understood hereafter to be a set of data carriedin the packets all having in common a same identifier, defined forexample by a pair (source address, destination address) or by a triplet(source address, destination address, port number).

Finally, a “packet-switched communication network” is understood here asan asynchronous communication network, such as for example a MPLS,GMPLS, ATM, Frame Relay (FR), TDMA, CDMA, IP network or a wired (or LAN(Local Area Network)—IEEE 802.3 standard) or wireless (or WLAN (WirelessLocal Area Network)) Ethernet network

PRIOR ART

As those skilled in the art know, some temporal constraint applicationsmust guarantee that data streams will be routed from one item ofcommunication equipment to another while respecting certain technicalcharacteristics, such as for example a maximum bandwidth and/or aminimum latency. This is particularly the case for “streaming”applications that consist in transmitting continuously, live or indeferred mode, a content (possibly multimedia) in order to be played onthe fly (and thus without the entirety of the content having beenreceived).

In order for an application with a temporal constraint to be able torespect technical characteristics, it is particularly necessary thatresources of the core network responsible for content transport arereserved for this purpose by one or several relaying nodes of thenetwork. “Relaying node” is understood here to be an item of equipmentbelonging to a communication core network and having a role in therelaying of stream packets, such as for example a “switch” or a“router”.

To reserve resources, following the reception of a resources reservationrequest from a running application, for example in an item ofcommunication equipment, a relaying node must first address anappropriate request to its network, then it must wait until theresources requested are accorded to it, which may at times require thatit cancels the resources previously reserved (and thus accorded). Itwill be appreciated that these operations are time consuming and thuslead to delays that may be incompatible with certain temporalconstraints of applications.

SUMMARY OF THE INVENTION

The purpose of the invention is therefore to improve the situation, andmore specifically to enable a pre-reservation of resources for therelaying nodes of a core network.

For this purpose, the invention initially proposes a method intended toaid in the reservation of resources with a packet-switched communicationnetwork comprising a number N of relaying nodes.

This method is characterized by the fact that it consists in:

-   -   determining for some at least of the N (relaying) nodes at least        resource reservation plan Pik defined by a plan identifier        associated with a stream identifier and at least two ports, and    -   in memorizing for each of the N nodes the various plans Pik        relating to them.

The method according to the invention can comprise other characteristicsthat can be taken individually or in combination, and particularly:

-   -   each time that one of the N nodes receives a message requesting        a new resource reservation or pre-reservation for a stream, a        new plan Pik can be determined for this node that is adapted to        this new reservation or pre-reservation,    -   in each node can be carried out, a determination of the plan Pik        that relates to it,    -   in the case of need for a determination of a new plan Pik for        one of the N nodes, to this new plan Pik a plan identifier can        be attributed for which the value is greater than a unit at the        highest value known for an existing plan identifier (within the        network),    -   in the case of a requirement for determination of a new plan Pik        for one of the N nodes, this node can attribute to this new plan        Pik a provisional plan identifier for which the value is greater        than a unit at the highest plan identifier value Pik′ existing        locally for it, then it can interrogate each of the N−1 other        nodes in order to determine if one among them has already a plan        Pi′k associated with this provisional plan identifier, and if        negative it can attribute to the new plan Pik this provisional        plan identifier, whereas in the affirmative it can attribute to        the new plan Pik a plan identifier for which the value is        greater than a unit at the highest known value of an existing        plan identifier (within the network),    -   a combination of N plans Pik that must be used respectively by        the N nodes can be determined from among all the plans Pik and        according to messages received,        -   a new combination of N plans Pik can be determined each time            a new plan Pik is determined for one of the N nodes,            following the reception by this latter of a message            requesting a new resource reservation or pre-reservation or            the end of a resource reservation for a stream,        -   the set of definitions of existing plans Pik can be stored            for each of the N nodes in an item of master equipment, and            each new combination of N plans Pik can be determined by            means of this master equipment,            -   the master equipment can determine for each of the N                nodes the plans Pik that relate to them in order to                update the set of existing plan Pik definitions that it                stores,            -   the master equipment can be determined from among the                candidate items of equipment,                -   the master equipment can for example be the                    candidate equipment that has the lowest IP address,            -   the master equipment can be determined from among the                network nodes that are candidates and/or from among the                items of communication equipment that are connected to                the relaying nodes and that are candidates.

The invention also proposes a device, dedicated to the management of thereservation of resources within a packet-switching communication networkcomprising N relaying nodes, and comprising the means for managementresponsible for determining a combination of N resource reservationplans Pik that must (or that can) be used respectively by the N(relaying) nodes, from among a set of resource reservation plans Pikassociated with these N nodes and each defined by a plan identifierassociated with a stream identifier and at least two ports of a relayingnode.

The management device according to the invention can comprise othercharacteristics that can be taken separately or in combination, andparticularly:

-   -   the management means can be responsible for determining a new        combination of N plans Pik each time it is alerted that a        relaying node has determined a new plan Pik following the        reception of a message requesting a new resource reservation or        pre-reservation or the end of a resource reservation for a        stream,    -   It can comprise the means for storage responsible for storing        the set of definitions of the existing plan Pik,        -   the management means may be responsible for determining for            each of the N (relaying) nodes, the plans Pik relating to            them in order to update the set of definitions of the            existing plan Pik that is stored in the storage means.

The invention also proposes an item of equipment, specifically to beconnected to a relaying node of a packet-switching communication networkor be part of this latter, and equipped with a management device of thetype presented above.

The invention also proposes a device, intended to aid in the reservationof resources of at least one relaying node of a packet-switchingcommunication network, and comprising:

-   -   means for calculation responsible for determining for this        relaying node, according to the messages that it has received        requesting a resource reservation or pre-reservation, at least        one resource reservation plan Pik, that this relaying node is        able to use, and that is defined by a plan identifier associated        with a stream identifier and with at least two ports of this        relaying node, and    -   Means for storage specific for storing each plan Pik definition        determined by the calculation means.

The aid device according to the invention can comprise othercharacteristics that can be taken separately or in combination, andnotably:

-   -   the calculation means can be charged, each time the relaying        node receives a message requesting a new resource reservation or        pre-reservation for a stream, with determining for this relaying        node a new plan Pik adapted to this new reservation or        pre-reservation,    -   the calculation means can be charged with attributing to a new        plan Pik a plan identifier for which the value is greater than a        unit at the highest value known of an existing plan identifier        (within the network),        -   the calculation means can be charged with attributing to a            new plan Pik relating to a relaying node a provisional plan            identifier for which the value is greater than a unit at the            highest plan identifier value Pik′ stored in the storage            means, then with ordering the interrogation of other            relaying nodes of the network in order to determine if one            among them already has a plan Pi′k associated with this            provisional plan identifier, then if the response is            negative, with attributing to this new plan Pik this            provisional plan identifier, and if the response is            positive, with attributing to this new plan Pik a plan            identifier whose value is greater than a unit at the highest            known value of an existing plan identifier (within the            network).

The invention also proposes a relaying node, for a packet-switchingcommunication network, equipped with an aid device of the type presentedabove.

BRIEF DESCRIPTION OF THE DRAWINGS

Other characteristics and advantages of the invention will appear uponexamination of the detailed description hereafter, and the annexeddrawings, wherein:

FIG. 1 shows in a diagrammatic and functional manner a partial exampleof the core of a wired local network of Ethernet/IP type comprising fouritems of switching equipment each equipped with an embodiment of the aiddevice according to the invention and of ports to which are connected,according to a first configuration, nine items of communicationequipment some of which are equipped with an embodiment of themanagement device according to the invention,

FIG. 2 shows in a diagrammatic and functional manner an example of atree structure defining the connections established between the items ofcommunication equipment and the items of switching equipment of FIG. 1,in accordance with the first configuration,

FIG. 3 is identical to FIG. 1, but with a second connectionconfiguration between the 4 items of switching equipment and the 9 itemsof communication equipment, and

FIG. 4 shows in a diagrammatic and functional manner an example of atree structure defining the connections established between the items ofcommunication equipment and the items of switching equipment of FIG. 3,in accordance with the second configuration,

The annexed drawings can be used not only to complete the invention, butalso to contribute to its definition, if necessary.

DETAILED DESCRIPTION

The purpose of the invention is to facilitate (if possible whileaccelerating) the reservation of resources within a packet-switchedcommunication network.

In what follows, it is considered, as a non-restrictive example, thatthe packet-switched communication network is a wired local network ofEthernet/IP type (or LAN (Local Area Network)—standard IEEE 802.3). But,the invention is not limited to this type of packet-switchedcommunication network. It relates in fact to any type of packet-switchedcommunication network, asynchronous, and particularly the networks oftype MPLS, GMPLS, ATM, Frame Relay (FR), TDMA, CDMA, IP and wirelessEthernet (or WLAN (Wireless Local Area Network)).

A non-restrictive example of a local wired core network CR of typeEthernet/IP comprising four relaying nodes Si (i=1 to 4) of ports towhich are connected, according to a first configuration, nine items ofcommunication equipment (or hosts) Hj (j=1 to 9).

In what follows, it is considered as a non-restrictive example that thefour relaying nodes S1 to S 4 are Ethernet/IP switches. But, theinvention is not limited to this type of relaying node. It relates infact to any type of equipment belonging to the communication corenetwork and having a role in the relaying of stream packets.Consequently, it can also involve routers for example.

Moreover, it is considered in what follows, as a non-restrictiveexample, that the items of communication equipment (or hosts) Hj areitems of studio equipment implicated in the creation of multimediacontents that must be broadcast in streaming mode. Consequently, it caninvolve cameras, delay servers, audio and/or video data players and/orrecorders, microphones, headphones, audio and/or video mixing tables, ormanagement computers. But, the invention is not limited to this type ofcommunication equipment. It relates in fact to any type of communicationequipment that can be connected to a relaying node Si of apacket-switched communication network. Consequently, it can also involvefixed or portable computers, audio and/or video content receivers(possibly of STB (Set-Top Box) or “Home Gateway” type), fixed or mobiletelephones, communicating digital personal assistants (or PDAs), orcontent servers.

It will be noted that the decision to connect items of communicationequipment Hj to switches Si is well adapted to application with a(strong) temporal constraint, such as for example audio and/or videostreaming applications. In fact, the switches are items of networkequipment that best rest the temporal constraints as they manage thetransfer of stream data packets according to the information contained,on the one hand, in their headers that belong to the layer 2 (transportlayer called the “data link” layer) of the OSI layers model, and on theother hand, in a transfer table (or “forwarding table”—a tableassociating a hardware address with a switch port).

The invention proposes implementing within the core of thepacket-switched communication network CR, comprising a number N ofrelaying nodes Si (here i=1 to 4, N=4), a method for aiding in thereservation of resources.

This method consists, on the one hand, in determining for some at leastof the N (relaying) nodes Si at least one resource reservation plan Pik(k≦1) that is defined by a plan identifier associated with a streamidentifier and at least two ports, and on the other hand, in memorizingfor each of the N (relaying) nodes Si the various plans Pik relating tothem.

The determination of a new plan Pik for a node Si is preferably madeeach time it receives a message requesting a new resource reservation orpre-reservation for a stream. This new plan Pik must then be adapted tothis new requested resource reservation or pre-reservation.

It will be noted that it is advantageous that each determination of aplan Pik is made at the level of the node Si that is able to be used.For this purpose, and as shown, each node Si can for example be equippedwith a resource reservation aid device D2.

It is understood here by “equipped” the fact to comprise internally, asshown non-restrictively, or to be connected to an aid device D2.

It is important to note that an aid device can be considered either ofcentralized type and thus adapted to the determination of reservationplans Pik for several or even all nodes SI.

An aid device D2, according to the invention, comprises a calculationmodule MC and storage means MS2.

The calculation module MC is charged with determining for its (one) nodeSi, according to messages that this latter has received requesting aresource reservation or pre-reservation, at least one resourcereservation plan Pik (as defined above).

It is important to note that the aforementioned messages have notnecessarily the aim of requesting immediate progression to thereservation of a resource. This may be the case. But, it is advantageousto provide for a sort of learning phase at the level of each node Si inorder to provide in advance for all the configurations that it mayencounter taking account of the items of communication Hj and othernodes Si′ that are paired to it, and thus to determine in advance areservation plan Pik for each possible configuration. Consequently, amessage can thus have as an objective to request a resource“pre-reservation”.

It is equally important to note that each reservation plan Pikpreferably also has a plan identifier that is unique within the corenetwork CR. A reservation plan Pik is in fact determined for a givennode Si. It thus corresponds to specific local resources of the node Si(as for example the filtering policies at input and output, the buffermemories at input and output, the priority rules and the shaping rulesthat must be used in order to ensure for the data streams a Quality ofService (QoS) in accordance with the requirements of the applicantapplication that is at the origin of said streams.

For example, a reservation plan Pik can be defined as follows:

Stream_spec {    Integer StreamId    Integer Port_number_Lst[ ] }Reservation_Plan {    Integer Reserv_Plan_Id    Stream_specData_flow_Lst[ ] },where “Stream_spec” relates to a stream designated by a streamidentifier “StreamId” and associated with a list of at least two portsof a node Si “Port_number_Lst” and “Reservation_Plan” relate to areservation plan designated by a plan identifier “Reserv_Plan_Id” (orPik) and relating to a stream constituted of a list of at least onestream of data packets “Data_flow_Lst”.

The storage means MS2 are intended to store each plan definition Pikthat was determined by the calculation module MC. Any storage meansknown to those skilled in the art can be used, and particularly a memory(possibly software). This storage can for example be made in the form ofa table of reservation plans Pik. It will be understood that such atable comprises the definition of at least one reservation plan Pik, andpreferably of several (for the reasons invoked above).

In the first connection configuration that is shown in FIGS. 1 and 2,there is:

-   -   a node S1 having its port 1 connected to the node S4 (with which        there is no stream relaying planned), the ports 2 and 4 are        respectively connected to the items of equipment H2 and H8        (source) (for the purpose of relaying the stream from the item        of equipment H8 to the item of equipment H2), and the ports 3        and 5 respectively connected to the nodes S2 and S3 (for the        purpose of relaying the stream from the item of equipment H6        (source) to the items of equipment H7 and H1),    -   a node S2 having the its ports 1 and 2 respectively connected to        the node S1 and the item of equipment H1 (for the purpose of        relaying the streams from the item of equipment H6 and intended        for the item of equipment H1) and it ports 3 and 4 respectively        connected the items of equipment H3 (source) and H5 (for the        purpose of relaying the stream from the item of equipment H3 to        the item of equipment H5),    -   a node S3 having its port 1 connected to the item of equipment        H6 (source) (for the purpose of relaying the stream from this        item of equipment H6) and the ports 2 and 3 respectively        connected to the node S1 (for the purpose of relaying the        streams from the item of equipment H6 and intended for the item        of equipment H1) and the item of equipment H7 (for the purpose        of relaying the streams from the item of equipment H6 and        intended for this item of equipment H7),    -   a node S4 having the ports 1 and 3 respectively connected to the        items of equipment H4 (source) and H9 (for the purpose of        relaying the stream from the item of equipment H4 to the item of        equipment H9), and its port 2 connected to the node S1 (with        which there is no stream relaying planned).

It will be understood that in this first connection configuration thereare four streams relayed via four nodes S1 to S4.

The first stream F1 relates to the items of equipment H2 to H8. It isshown in FIGS. 1 and 2 by thick dotted and continuous lines.

The second stream F2 relates to the items of equipment H1, H6 and H7. Itis shown in FIGS. 1 and 2 by discontinuous (dashes) lines.

The third stream F3 relates to the items of equipment H3 to H5. It isshown in FIGS. 1 and 2 by dotted lines.

The fourth stream F4 relates to the items of equipment H4 to H9. It isshown in FIGS. 1 and 2 by discontinuous lines (alternating dashes anddouble-dots).

But, a second connection configuration of the type shown in FIGS. 3 and4 can also be considered.

In this second connection configuration, there is:

-   -   the node S1 that has its port 1 connected to the node S4 (for        the purpose of relaying streams from the item of equipment H4        and intended for the item of equipment H8), the ports 2 and 4        respectively connected to the items of equipment H2 and H8 (for        the purpose of relaying streams from the item of equipment H8 to        the item of equipment H2), and the ports 3 and 5 respectively        connected to the nodes S2 and S3 (for the purpose, on the one        hand, of a relaying of streams from the item of equipment H6 and        intended for the item of equipment H1, and on the other hand, a        relaying of the streams from the item of equipment H3 and        intended for the item of equipment H7),    -   a node S2 that has its ports 3 and 4 respectively connected to        the items of equipment H3 (source) and H5 (for the purpose of        relaying streams from the item of equipment H3 to the item of        equipment H5), and its ports 1 and 2 respectively connected to        the node S1 and the item of equipment H1 (for the purposes, on        one hand, of relaying the streams from the item of equipment H6        and intended for the item of equipment H1, and on the other        hand, of relaying the streams from the item of equipment H3 and        intended for the item of equipment H7),    -   a node S3 having its port 1 connected to the item of equipment        H6 (source) (for the purpose of relaying the streams from this        item of equipment H6 and intended for the item of equipment H1),        and the ports 2 and 3 respectively connected to the node S1 (for        the purpose of relaying the streams from the item of equipment        H6 and intended for the item of equipment H1) and to the item of        equipment H7 (for the purpose of relaying the streams from the        item of equipment H3 and intended for this item of equipment        H7),    -   a node S4 having the ports 1 and 3 respectively connected to the        items of equipment H4 (source) and H9 (for the purpose of        relaying the stream from the item of equipment H4 to the item of        equipment H9), and its port 2 connected to the node S1 (for the        purpose of relaying the streams from the item of equipment H4        and intended for the item of equipment H8).

It will be understood that in this second connection configuration thereare also four streams relayed via four nodes S1 to S4.

The first stream F1 relates to the items of equipment H2 to H8. It isshown in FIGS. 3 and 4 by thick dotted and continuous lines.

The second stream F2 relates to the items of equipment H1 and H6. It isshown in FIGS. 3 and 4 by discontinuous (dashes) lines.

The third stream F3 relates to the items of equipment H3 H5 and H7. Itis shown in FIGS. 3 and 4 by dotted lines.

The fourth stream F4 relates to the items of equipment H4, H8 and H9. Itis shown in FIGS. 3 and 4 by discontinuous lines (alternating dashes anddouble-dots).

Due to these first and second possible connection configurations, thefollowing tables of reservation plans Pik (or Reserv_Plan_Id) can beestablished:

-   -   for the node S1:

Reserv_Plan_Id StreamId Port_Number_Lst 1 1 2, 4 2 3, 5 5 1 2, 4 2 3, 53 3, 5 4 1, 4

-   -   for the node S2:

Reserv_Plan_Id StreamId Port_Number_Lst 2 2 1, 2    3 3, 4    6 2 1,2    3 1, 3, 4

-   -   for the node S3:

Reserv_Plan Id StreamId Port_Number_Lst 3 2 1, 2, 3 7 2 1, 2    3 2,3   

-   -   for the node S4:

Resery_Plan_Id StreamId Port_Number_Lst 4 4 1, 3    8 4 1, 2, 3

It is deduced from the preceding tables, that at a given instant thereis a set of eight reservation plans Pik that have been determined forthe four nodes S1 to S4 of the core network CR (but only four of themare used (and therefore active) at this given instant). The reservationplans having the plan identifiers (Reserv_Plan_Id) 1 and 5 correspondrespectively to P11 and P15 and can be used by the node S1. Thereservation plans having the plan identifiers (Reserv_Plan_Id) 2 and 6correspond respectively to P22 and P26 and can be used by the node S2.The reservation plans having the plan identifiers (Reserv_Plan_Id) 3 and7 correspond respectively to P33 and P37 and can be used by the node S3.The reservation plans having the plan identifiers (Reserv_Plan_Id) 4 and8 correspond respectively to P44 and P48 and can be used by the node S4.

The attribution of plan identifiers (Reserv_Plan_Id) to the differentreservation plans Pik can be carried out as indicated hereafter.

When a new reservation plan Pik must be determined for one of the Nnodes Si, a plan identifier can be attributed to it for which the valueis higher than a unit of the highest value known of a plan identifierexisting in the core network CR. For example, if it is known that thehighest plan identifier value is equal to 5, a plan identifier valueequal to 6 (or 5+1) will be attributed to the new reservation plan Pik.

It will be understood that in the presence of an aid device D2 in a nodeSi, it is its calculation module MC that will determine the value thatit must attribute to the plan identifier of each new reservation planPik.

To do this, the aid device D2 can be informed by the core network CR ofall the plan identifier values that have already been attributed. But,it may proceed in a different way in the absence of such information. Infact the calculation module MC of a node Si (having need of a new planPik) can for example begin by attributing to this latter a provisionalplan identifier whose value is higher than a unit at the highest planidentifier value attributed to a reservation plan Pik of the table(local) that is stored in the storage means MS2 of its aid device D2.Then, it can command its node Si to interrogate each of the N−1 othernodes Si′ (i′≠i) of the core network CR, in order to determine if one ofthem already has a plan Pi′k that is associated with this provisionalplan identifier. Thus, in the negative it can then, after havingpossibly waited the extent of a selected timeout, it can definitivelyattribute the provisional plan identifier to this new plan Pik. However,in the affirmative, after having possibly waited the extent of theselected timeout, it attributes to the new plan Pik a plan identifierfor which the value is higher than a unit of the highest value known ofexisting plan identifiers within the core network CR.

Any message type, in accordance with a protocol used in the core networkCR, can be used by a node Si to interrogate the N−1 other nodes Si′.Thus, it may for example involve a BPDU (Bridge Protocol Data Unit) typemessage containing the value of the provisional plan identifier that isintended to be attributed to a new plan Pik.

Likewise, each interrogated node Si′ can respond to the node Si thatinterrogated it using any message type, as long as it is in accordancewith a protocol used within the core network CR. Thus, each interrogatednode Si′ can for example respond to a BPDU message with a “NACK BPDU”type message that indicates the highest value of a plan identifier valuestored in the storage means MS2 of its aid device D2 if it is higherthan that contained in the received BPDU message.

It will be noted that an aid device D2, according to the invention, canbe realized in the form of a combination of software modules andhardware, or of hardware or of software.

At a given instant the N nodes Si use respectively N reservation plansPik of a combination that was determined at a preceding instant fromamong the reservation plans previously determined and for which thedefinitions were for example stored at this preceding instant in thetables of the storage means MS2 of the aid devices D2 of the N nodes Si.

A combination of N plans Pik for N nodes Si of the network core CRconstitutes a global configuration (that itself can be seen as a type ofglobal reservation plan). More specifically, a global configuration CGcan be defined as the stable set of all the reservation plans that canbe simultaneously active over a non-null period of time. It is in factimportant to note that a combination is constituted of N mutuallycompatible plans.

For example, each determination of a new combination of N plans Pik canbe carried out following the transmission by one of the N nodes Si of amodification notification of one of the related plans Pik. It will benoted that such a modification may result in the reception beforehand bythe node Si of a message requesting a new resource reservation orpre-reservation for a stream that it must relay or the end of a resourcereservation for a stream that it has just relayed.

It is important to note that a new global configuration (or combination)CG is constituted, with respect to a new global configuration (orcombination) previously calculated, of at least the new plan Pik that isthe origin of the transmission by one of the N nodes Si of amodification notification, and possibly of one or several other plansPi′k (previously identified).

The determinations of (new) combinations of N plans Pik, constitutingglobal configurations CG, that can for example be made centrally in amaster item of equipment, equipped for this purpose with a managementdevice D1 according to the invention.

It is understood here by “equipped” the fact of comprising internally,as shown non-restrictively, or to be connected to a management deviceD1.

In the non-restrictive example shown in FIGS. 1 and 3, the managementdevices D1 have been implanted in some items of communication equipment(H1, H2, H4, H5, H6 and H8). But, management devices D1 can be implantedin at least one of the items of communication equipment Hj and/or in atleast one of the nodes of the core network CR (and for example in arelaying node Si). Consequently, one at least of the nodes Si canpossibly be equipped both with an aid device D2 and a management deviceD1.

When there is only one item of equipment that has a management deviceD1, it is thus automatically the master item of equipment. However, whenseveral items of equipment (Hj and/or Si) have a management device D1,it is preferable that one among them is selected to assure the role ofmaster item of equipment.

For example, this selection can be made among the items of equipmentthat are candidates. A candidate item of equipment is for example anitem of equipment equipped with a management device D1 and thattransmits in broadcast mode, and thus to all the other items ofequipment, a specific message, for example of PDU (Protocol Data Unit)type, to notify them of its desire to assure the role of master.

As a non-restrictive example, that which has the lowest IP address canbe selected from among the candidates. In a variant, the mastercandidate can be selected according to the “weight” (shortest path,maximal bandwidth, etc.) of the set of links that associates it withother nodes of the network or items of equipment Hj. In another variant,the master candidate can be selected arbitrarily and “manually”, forexample using a parameter of a “MIB SNMP”.

A management device D1, according to the invention, comprises amanagement module MG and storage means MS1.

Following the transmission by one of the N nodes Si of a modificationnotification of one of the plans Pik relating to it, the managementmodule MG determines a new combination of N resource reservation plansPik for N nodes Si. To do this, it determines the N plans of the newcombination from among the set of definitions of all the resourcereservation plans Pik that are associated with these N nodes Si, takingaccount of N plans that they are using respectively, and thus that areactive, and taking account of said new plan.

For example, the storage means MS1 store the set of definitions of allthe resource reservation plans Pik that are associated with these Nnodes Si. They are for example updated, possibly periodically, by themanagement device D1, following the interrogation of N nodes Si by itsmaster item of equipment.

Moreover, in order to know precisely the (active) plans Pik that areused by the N nodes Si at a given instant, the management module MG canfor example command its master item of equipment to address to the Nnodes Si, in broadcast mode, a message requesting that each of themtransmit the definition of the (active) plan Pik that it is using.

It will be noted that a new combination (or global configuration) CG canpossibly comprise one or several plans identical to those used in acombination (or global configuration) previously determined (andpossibly being used) by the N nodes Si.

If the new determined combination (or global configuration) CG must beapplied, then it proceeds to the switching from the old combination (orglobal configuration), to this new combination (or globalconfiguration). In this case, the management device D1 of the masteritem of equipment commands this latter to address to the N nodes Si, inbroadcast mode, a message (for example of PDU type) containing the listof N plan identifiers that they must immediately apply. When a node Sireceives this message, it locally manages its internal resources(particularly its input and output buffer memories) so that they areadapted to the plan Pik of the new combination that it must use (it willbe understood that a node Si has nothing to adapt when it is requestedto use the same plan as it has just been using).

It will be noted that a management device D1, according to theinvention, can be realized in the form of a combination of softwaremodules and hardware, or of hardware, or again of software modules.

The invention is not limited to the embodiments of the managementdevice, aid device, communication equipment, relaying node and aidmethod described above, only as an example, but it encompasses all thevariants that those skilled in the art can envisage within the frameworkof the claims that follow hereafter.

1-22. (canceled)
 23. Method for reserving resources for apacket-switched communication network comprising a number N of relayingnodes, said reservation being established following a reservation plan,wherein consists in: i) determining for each of said N nodes at leastone resource reservation plan Pik defined by a plan identifierassociated with a stream identifier and with at least two ports, and inii) memorizing for each of said N nodes the different plans Pik relatedto them.
 24. Method according to claim 23, wherein each time that one ofthe N nodes receives a message requesting a new resource reservation orpre-reservation for a stream, a new plan Pik can be determined for thisnode that is adapted to this new reservation or pre-reservation. 25.Method according to claim 23, wherein each plan Pik determinationrelating to a node is carried out in the node.
 26. Method according toclaim 23, wherein in the case of a requirement for a determination of anew plan Pik for one of said N nodes a plan identifier for which thevalue is greater than a unit at the highest known value of an existingplan identifier is attributed to this new plan Pik.
 27. Method accordingto the combination of claim 25, wherein in the case of a requirement fordetermination of a new plan Pik for one of said N nodes, this nodeattributes to this new plan Pik a provisional plan identifier for whichthe value is greater than a unit at the highest plan identifier valuePik′ existing locally for it, then it interrogates each of the N−1 othernodes in order to determine if one among them has already a plan Pi′kassociated with this provisional plan identifier, and if negative itattributes to the new plan Pik said provisional plan identifier, whereasin the affirmative it attributes to said new plan Pik a plan identifierfor which the value is greater than a unit at the highest known value ofan existing plan identifier.
 28. Method according to claim 23, wherein acombination of N plans Pik that must be used respectively by said Nnodes is determined from among all said plans Pik and according tomessages received.
 29. Method according to claim 28, wherein a newcombination of N plans Pik is determined each time a new plan Pik isdetermined for one of said N nodes, following the reception by thislatter of a message requesting a new resource reservation orpre-reservation or the end of a resource reservation for a stream. 30.Device for managing resource reservation for a packet-switchedcommunication network comprising N relaying nodes, said reservationbeing established following a reservation plan, wherein it comprisesmanagement means arranged to determine a combination of N resourcereservation plans Pik that must be used respectively by said N nodes,from among a set of resource reservation plans Pik associated with saidN nodes and each defined by a plan identifier associated with a streamidentifier and at least two ports of a relaying node.
 31. Deviceaccording to claim 30, wherein said management means are arranged todetermine a new combination of N plans Pik each time it is alerted thata relaying node has determined a new plan Pik following the reception ofa message requesting a new resource reservation or pre-reservation orthe end of a resource reservation for a stream.
 32. Item of equipment,able to be connected to a relaying node of a packet-switchedcommunication network or to be part of the latter, wherein it comprisesa management device according to claim
 30. 33. Device for reservingresources for at least one relaying node of a packet-switchedcommunication network, said reservation being established following areservation plan, wherein it comprises: i) calculation means arranged todetermine for said relaying node, according to messages that it receivedrequesting a resource reservation or pre-reservation, at least oneresource reservation or pre-reservation plan Pik, that said relayingnode is able to use and that is defined by a plan identifier associatedwith a stream identifier and at least two ports of said relaying node,and ii) storage means able to store each plan definition Pik determinedby said calculation means.
 34. Device according to claim 33, whereinsaid calculation means are so arranged that, each time the relaying nodereceives a message requesting a new resource reservation orpre-reservation for a stream, to determine for this relaying node a newplan Pik adapted to this new reservation or pre-reservation.
 35. Deviceaccording to claim 33, wherein said calculation means are arranged toattribute to a new plan Pik a plan identifier for which the value isgreater than a unit at the highest value known of an existing planidentifier.
 36. Device according to claim 35, wherein said calculationmeans are arranged to attribute to a new plan Pik relating to a relayingnode a provisional plan identifier for which the value is greater than aunit at the highest plan identifier value Pik′ stored in the storagemeans, then to order the interrogation of other relaying nodes of saidnetwork in order to determine if one among them already has a plan Pi′kassociated with this provisional plan identifier, then if the responseis negative, to attribute to this new plan Pik said provisional planidentifier, and if the response is positive, to attribute to this newplan Pik a plan identifier whose value is greater than a unit at thehighest known value of an existing plan identifier.
 37. Relaying nodefor a packet-switched communication network, wherein it comprises areservation device according to claim 33.